We have studied the features of periodical poling by focused electron beam irradiation of MgO-doped lithium niobate (MgOLN) single crystalline plate covered by the resist layer. We have distinguished the main types of the domain structure depending on the irradiated dose. We have revealed that total domain area and width of the domain stripes depend linearly on the dose and irradiated stripe width. We have observed the highly regular domain structures with duty-cycle close to desirable value of 0.5 on both polar surfaces.